Circuit arrangement for thermionic tubes



Jan. 15, 1935. P. J. H. A. NORDLOHNE ET AL 1,987,963

CIRCUIT ARRANGEMENT FOR THERMIONIC TUBES Filed July 28, 1930 INVENTORS v PlERRE JANNE HENRI ALPHONSE MOLD! BRYINZE HENDNK VAN WNNEN Patented Jan. 15, 1935 UNITED STATES CIRCUIT ARRANGEMENT FOR THERMIONIC TUBES Pierre J anne Henri Alphonse N ordlohne and Rinze Hendrik van Minnen, Eindhoven, Netherlands,

assignors to Radio Corporation of America, a

corporation of Delaware Application July 28, 1930, Serial No. 471,308 In the Netherlands July 27, 1929 1 Claim.

(Granted under the provisions of sec. 14, act of March 2, 1927; 357 0. G.

The present invention relates to amplifier circuits generally and more specifically to amplifier circuits adapted for use in short wave work.

, In circuit arrangements for thermionic devices,

5 for example for amplification purposes, use is frequently made of a tuned anode circuit. In this case the anode circuit includes a tuned circuit which comprises an inductance shunted by a capacity. However, with the very high frequencies frequently used at the present day, the efliciency of this circuit arrangement is not very high by reason of the circumstance that the total capacity which is in parallel with the inductance is fairly high. Thus the external resistance decreases so that the efiiciency is lowered.

The invention provides means for increasing the efliciency of such circuits and consists in that the tuning condenser instead of being connected in parallel to the inductance coil, is connected in series therewith.

In order that the invention may be clearly understood and readily carried into efiect one embodiment will be described more fully with reference to the accompanying drawing the single figure of which shows in diagrammatic form a preferred embodiment of the invention.

Referring to the Figure, 1 designates a triode comprising a cathode 2, a grid 3 and an anode 4. The anode circuit includes a battery 5 in series with a choke coil 6. 7 designates an inductance coil, 8 a variable condenser which in this case is interconnected between the cathode and the end of the inductance 7 that is not connected to the anode. 9 designates the effective capacity between the anode and the cathode. The tuned circuit is constituted by the elements 7, 8 and 9.

It is, of course, obvious that as an alternative the choke coil 6 may pass directly from the positive terminal of the anode battery to the anode.

In this case, however, the capacity of the oscillatory circuit is slightly higher on account of 5 the natural capacity of the combination batterychoke coil which is in parallel with the internal triode capacity.

There is another advantage of the new circuit arrangement in that one of the sets of electrodes 10 of the tuning condenser can be connected to the cathode and consequently be earthed, at least in the most usual circuit arrangement.

We claim:-

An amplifier circuit especially for use in short 15 wave work comprising an electron discharge tube provided with anode, cathode and grid electrodes,

a tunable circuit for said amplifier comprising an inductance coil and a variable tuning condenser connected in the order named in series between 20 the anode and cathode of the tube, said tunable circuit including also the natural inherent capacity between the anode and cathode of the tube said capacity being efiectively shunted across the inductance and condenser, a circuit comprising a 25 source of space current for the tube and a choke coil in series said last named circuit being shunted across the condenser only, the total effective capacity across the inductance coil being small as compared to the capacity of the tuning con- 30 denser whereby the impedance of the tuned circuit is maintained sufficiently high to cause the circuit to operate efficiently.

PIERRE J ANNE HENRI ALPHONSE NORDLOHNE. RINZE HENDRIK VAN MINNEN. 

